Unicode emojis are throwing off emote replacement

[BenDMyers]

Unicode emojis (as in, the emojis you use your device's native emoji keyboard to type) are messing with the string replacement indices for adding emote <img> strings to the message. This appears to be because emojis are multiple bytes (at least two, sometimes more depending on the emoji). Multiple emojis cause the emote <img> string replacement to be even more offset.

A few examples:

🦖 somean3CoolTuna

• Result: 🦖a
• Result as HTML string:

🦖<img alt=" somean3CoolTun" data-twitch-emote=" somean3CoolTun" data-twitch-emote-id="emotesv2_3e72737cb25d4278971dd4988b48992c" src="https://static-cdn.jtvnw.net/emoticons/v2/emotesv2_3e72737cb25d4278971dd4988b48992c/default/light/3.0">a

• Expected: 🦖
• Expected HTML string:

🦖 <img alt="somean3CoolTuna" data-twitch-emote="somean3CoolTuna" data-twitch-emote-id="emotesv2_3e72737cb25d4278971dd4988b48992c" src="https://static-cdn.jtvnw.net/emoticons/v2/emotesv2_3e72737cb25d4278971dd4988b48992c/default/light/3.0">

---

🦖 🦖 🦖 🦖 hellooooooooo somean3A11Y

• Result: 🦖 🦖 🦖 🦖 hellooooooA11Y
• Result as HTML string:

🦖 🦖 🦖 🦖 helloooooo<img alt="ooo somean3" data-twitch-emote="ooo somean3" data-twitch-emote-id="emotesv2_c13dfc82e82d4c05b41f1dfde9dbd38e" src="https://static-cdn.jtvnw.net/emoticons/v2/emotesv2_c13dfc82e82d4c05b41f1dfde9dbd38e/default/light/3.0">A11Y

• Expected: 🦖 🦖 🦖 🦖 hellooooooooo
• Expected HTML string:

🦖 🦖 🦖 🦖 hellooooooooo <img alt="somean3A11Y" data-twitch-emote="somean3A11Y" data-twitch-emote-id="emotesv2_c13dfc82e82d4c05b41f1dfde9dbd38e" src="https://static-cdn.jtvnw.net/emoticons/v2/emotesv2_c13dfc82e82d4c05b41f1dfde9dbd38e/default/light/3.0">